Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Back Home & Aten Ahead
Organization: Travelers in The Night
Link : Travelers in the Night
Description: Today’s 2 topics: Near Earth Object: WT1190F & Aten asteroid 2016 AK193
Bio: Dr. Al Grauer is currently an observing member of the Catalina Sky Survey Team at the University of Arizona. This group has discovered nearly half of the Earth approaching objects known to exist. He received a PhD in Physics in 1971 and has been an observational Astronomer for 43 years. He retired as a University Professor after 39 years of interacting with students. He has conducted research projects using telescopes in Arizona, Chile, Australia, Hawaii, Louisiana, and Georgia with funding from NSF and NASA.
He is noted as Co-discoverer of comet P/2010 TO20 Linear-Grauer, Discoverer of comet C/2009 U5 Grauer and has asteroid 18871 Grauer named for him.
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Transcript:
223 – Back Home
When my Catalina Sky Survey teammate Rose Matheny started tracking a rapidly moving point of light in the night sky she had no idea that it would collide with planet Earth 41 days later. Rose’s observations along with data taken by telescopes around the world were used to calculate the mystery object’s path through space. These new data along with observations made in previous years of an object which had been tracked and lost several times were used to predict an impact over the ocean south of Sri Lanka. The fireball occurred right on schedule.
We now have some clues about the properties of Rose’s object WT1190F. From its orbit it must have had a density of about a tenth that of water. The United Arab Emirates Space agency chartered a plane which enabled the scientists aboard to photograph WT1190F as it broke up and burned at high altitude. The spectrum obtained by these researchers indicated the presence of titanium oxide and hydrogen. These clues are consistent with what would be expected if WT1190F had been a spent rocket casing.
The question then became, “which rocket?”. It is unlikely that a discarded piece from an Apollo mission could have survived in WT1190F’s orbit for 40 plus years without colliding with the Earth or going into orbit around the Sun. Speculation is that WT1190F was a spent rocket which had been used to propel the NASA Prospector Satellite to the Moon in 1998.
In any event WT1190F enters the history books as the third object which was detected in outer space before entering the Earth’s atmosphere.
224- Aten Ahead
Asteroids travel in elliptical orbits about the Sun . About 6% of the Earth approaching asteroids we discover have an orbit which causes them to spend much of their time closer to the Sun than our home planet. They are called Atens. About one hundred of them are large enough and can come close enough to be considered potentially hazardous to humans.
Recently my Catalina Sky Survey teammate Carson Fuls discovered a 470 foot diameter, potentially hazardous Aten asteroid, now called 2016 AK193. It orbits the Sun once every 296 days on a path that takes it from inside the orbit of Venus out to 10% further from the Sun than the planet Earth. When Carson first spotted 2016 AK193 it was ten million miles from him traveling towards the Earth at 6.6 miles per second. Subsequently it was tracked by telescopes at 14 observatories around the world as it made its approach to planet Earth. Turns out that this large space rock had visited the Earth’s neighborhood in 1917 and 1930 not to return again until 2016. It will not come this close again until 2115.
Fortunately Carson’s discovery does not come closer to us than about 15 times the distance to our moon. One its size strikes the Earth every 16,000 years or so making a crater a mile and a half in diameter.
Aten asteroids spend most of their time inside the Earth’s orbit, come close to us, travel at speeds our rockets can match, and may be an economical source of raw materials for space exploration.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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Title: Travelers in the Night Digest: Back Home & Aten Ahead